Traditionally, the understanding among scholars and practitioners has been that a portfolio of NPD projects is the expression of a firm's strategy and thus it must support the strategy. In keeping with this view, the current study focuses on new product development (NPD) portfolio planning, which is defined as a firm's effort to formulate portfolio decisions using a defined innovation strategy. Connecting portfolio decisions to a defined innovation strategy has been associated with higher innovation success. Surprisingly, empirical research indicates that portfolio decisions do not always support the company's innovation strategy. Furthermore, during recent years, an increasing number of authors underscore the importance of responsiveness and adaptability in portfolio decision‐making. The current study addresses these two issues by examining a direct effect of decentralization in strategy‐making on NPD portfolio planning, and a moderating effect of decentralization in strategy‐making on the relationship between NPD portfolio planning and NPD program success. The study also examines the influence of national culture on the proposed relationships. The theoretical model was tested using data from the 2012 PDMA Comparative Performance Assessment Study. Findings indicate that NPD portfolio planning positively influences NPD program success. Also, results revealed inverted U‐shaped direct and moderating effects, respectively, of decentralization in strategy‐making on NPD portfolio planning, and of decentralization in strategy‐making on the relationship between NPD portfolio planning and NPD program success. With regard to the moderating effect of national culture, results indicate that uncertainty avoidance does not moderate the relationship between NPD portfolio planning and NPD program success. Nonetheless, we found significant moderating effects of individualism and power distance on the curvilinear relationship between decentralization in strategy‐making and NPD portfolio planning.